For emission reduction of an internal combustion engine, a fuel injection valve (injector) that feeds fuel to the engine is required to precisely meter an injection quantity, thereby suppressing uncontrollable fuel injection. To that end, the injector is required to reduce its quantity of fuel injected while a valve element bounces on a valve seat during valve closing.
A conventional fuel injection valve that is publicly known injects the fuel from its injection hole through use of magnetic attraction force generated by energization of a coil.
In such a fuel injection valve, when the coil is energized, the magnetic attraction force is generated between a fixed iron core and a movable iron core. With the magnetic attraction force generated between the movable iron core and the fixed iron core, the movable iron core is attracted toward the fixed iron core, and force is transmitted to a valve element integral with the movable fixed iron core, thereby moving the valve element in a direction away from a valve seat. The movable iron core and the valve element that are integral with each other have their movement restricted by collision with the fixed iron core, thus identifying their stop positions. In this case, the movable iron core integral with the valve element collides with the fixed iron core and bounces back from the fixed iron core on impact of the collision. When the energization of the coil is brought to a halt, the magnetic attraction force acting between the movable iron core and the fixed iron core disappears, and when the magnetic attraction force becomes smaller than elastic force of an elastic member urging the valve element, the valve element starts to move toward the valve seat, that is to say, in a valve closing direction. The valve element and the movable iron core have their movement restricted by collision of the valve element with the valve seat, thus identifying their resting positions. In this case, the valve element collides with the valve seat and on impact of this collision, moves in the direction away from the valve seat. In cases where a space results between the valve element and the valve seat, uncontrollable fuel is injected exteriorly from the injection hole.
To suppress such uncontrollable fuel injection, a structure such as disclosed in PTL 1 includes a movable iron core and a valve element that are provided separately.